i've been waiting for months for B&H to get stock and finally ordered elsewhere at $600 -- and shortly after i received the lens, B@H has stock at $550!

actually, i've tested 2 copies which have very little between them (on 5D2) and are consistent with the Photozone test and Lloyd Chamber's report.

i was primarily looking for a lens to replace the 17-40 for travel as it's one too many bulky lenses in the bag that doesn't get used a lot -the 17-40 as a bit better center resolution but both are good enough that this isn't an issue -the 20 is better in the corners than the 17-40 at f4, but not as good at f8, but you've got to do some serious pixel peeping to see a difference -both have significant CA in the corners -both have mustache distortion although the 17-40 is more barrel with a little pincushion at the corners, while the 20 splits the barrel and pincushion and has a sharp distortion up-turn in the corners

as a reality check i compared my Sigma 12-24 and the Tokina 11-16 (on 7D) -my Sigma is not a particulary good copy and was significantly worse in all respects -the 11-16 and 7D was not as sharp (but sharp enough) in the center (as expected) but was comparable in the corners (the 17-40 and 20 had the same relative performance at 32mm effective on the 7D as the 5D, but most of the mustache is cropped out along with the worst of the CA)

Photozone and Lloyd Chambers agree that the Zeiss 18 is much better in the corners at larger apertures, but not significantly different stopped down to f8

the build quality and feel of the focusing ring of the 20 is outstanding, but the $50 lens hood can't be used with a lens cap (on the other hand the huge diameter of the 17-40 lens hood is a continual nuisance)

in general, the autofocus and versatility of the 17-40, at reasonable cost make it a clear choice if you don't mind the weight and bulk - although i must add that you should test the lens carefully (time consuming) - as is characteristic of wide angle zooms, manufacturing tolerances often result in seriously assymtercal performance which can vary with focal length. mine has been to Canon once under warranty and they improved some focal lengths and made some worse - and it will be going back again.

the Voigtlander 20 is no bargain even at the B&H price (on the other hand look at the cost in $, size, and weight to get better large aperture coner performance with the Zeiss 18)

if you can live with manual focus, the Voigtlander 20 and 40 paired with T2i seem a reasonable compact, light weight alternative to the lower performance 4/3 cameras

i'd like to see a reasonable sized wide angle prime with minimal distortion and excellent corner sharpness, but since i don't see this happening soon i'm going to give the Voigtlander 20 a try

Never tried the 20, but owned the 40 and 58 used via an adapter on Canon. Sold them (I shoot primarily alternates on Canon) as the reverse operation (vs Leica, Mamiya, CY, etc) kept catching me when I was in a hurry. The 40's aperture ring was also so tight to the body that operation was a PITA.

That said, I vowed to replace both when they came out in EoS. Very smooth operation, very sharp, compact, well built, with great bokeh -- just excellent all around. Also owned the entire SL1 line (75 thru 180 APO) at one time and sold them as prices peaked thinking a) due to reverse operation things had gotten nuts in the $$ department and c) eventually they would be re-issued in SLII, killing prices.

At same time vowed to replace them in SLII as well in EoS mount - or if ever moved to Nikon. Over the next 6 mos I'll likely pick up the 40/2 & 90/3.5 in EoS and later the 58, 180 (also stellar) and maybe the 125 (was only unit I never really took to) when/if they're released in SLII EoS mount. The 40 and 90 (stellar glass) would be a great compact 2-lens travel kit for say a 5D_, etc.

I own both the 20 and 40 for my Canon 5D2. I posted something on this a few weeks ago when I purchased the lenses from a Montreal dealer. My only other lens is the 24-105.

The 24-105 is a great lens, etc. etc. but before moving to photographing digitally I mainly used a 35 mm Summicron and a 50 Summicron. The package difference is rather substantial and obvious. The 40 Voigtlander splits the difference in focal length and makes for a much less obtrusive piece of equipment. No real issues with focussing, and the dof scale is fine as long as you compress it by a stop or so. I actually went and made comparison images with the 24-105 at 40 mm. The VC was actually better, mind you, that was on a tripod and using LiveView for focussing the VC. There is much to be said for autofocus and IS.

The 20 is a neat lens. Yes it has the moustache distortion, but so does the 24-105 at 24 mm. Focusing is definitely not an issue, at any f/stop. The shade is a bit of a pricey metal ring but I bought it anyway. According to a supplier in France the Heliopan makes a 72 mm cap that fits over the hood. I lucked in and found a shallow round metal box that held some fridge magnets, once lined with a bit of velvet it is a perfect fit.

I am impressed with the solid quality of both lenses, as I am of a 21 mm that I purchased a few years ago to use on my Leica's. And, since everything else but the final print is rather moot, I very much like the results these lenses (and the 24-105) allow me to produce.